AB0332 EVALUATION OF THE RABBIT RISK SCORE IN JAPANESE PATIENTS WITH RHEUMATOID ARTHRITIS NEWLY TREATED WITH BIOLOGIC DMARDS: DATA FROM THE IORRA COHORT
Authors: T. Higuchi, E. Tanaka, E. Inoue, M. Abe, K. Saka, E. Sugano, N. Sugitani, Y. Shimizu, M. Ochiai, R. Yamaguchi, K. Ikari, Y. Hisashi, M. Harigai
Journal: Annals of the Rheumatic Diseases (2022)

Background Serious infection is one of the most critical adverse events in patients with rheumatoid arthritis (RA) using biologic disease-modifying antirheumatic drugs (bDMARDs). During the first year, infections occur more frequently. Therefore, estimating the risk of developing a serious infection is important for the safe use of bDMARDs. The Rheumatoid Arthritis Observation of Biologic Therapy (RABBIT) risk score predicted the incidence rate of serious infection during 1 year in patients with RA taking DMARDs. Moreover, it has been validated using data from various observational cohort studies and nationwide registries with favorable results, with a reported area under the receiver operating characteristic curve (AUROC) of 0.68–0.87 1–5 . However, the RABBIT risk score has not been validated in RA patients starting a first bDMARD. Objectives To investigate the discriminatory ability of the RABBIT risk score for predicting the development of serious infection during 1 year after starting first bDMARDs in Japanese patients with RA using data from the Institute of Rheumatology, Rheumatoid Arthritis (IORRA) cohort. Methods The IORRA cohort is a large observational cohort at the Institute of Rheumatology, Tokyo Women’s Medical University. Japanese patients with RA visiting our institute were registered and clinical parameters were assessed biannually. This study enrolled patients with RA who were registered in the IORRA cohort and treated with a first bDMARD. Patients who were missing data needed to calculate the RABBIT risk score were excluded. The RABBIT risk score was calculated using the patient’s age, comorbidities, Japanese-Health Assessment Questionnaire score, history of previous infections, and types of DMARDs used. Serious infections were defined as those requiring hospitalization or treatment with intravenous antibiotics. The occurrence of serious infection during 1 year after starting the first bDMARDs was identified using data from the biannual IORRA cohort and confirmed using medical records. The discriminatory ability of the RABBIT risk score was analyzed by the AUROC. Results A total of 1,081 patients with RA and a median age of 55.3 years, in which females were the majority (88.2%), were included. Serious infection occurred in eight patients during 1 year before starting their first bDMARDs. The number of patients starting a TNF inhibitor, IL-6 inhibitor, and abatacept were 830 (76.8%), 170 (15.7%), and 81 (7.5%), respectively. A total of 23 patients (1.7%) had serious infections during 1 year after starting the first bDMARD; the most frequent infection was pneumonia (n=16, 69.6%). The median RABBIT score was 2.3 (IQR 1.6–5.4) in patients with serious infections during the follow-up period, and 1.6 (IQR 1.2–2.5) in patients without serious infections. The discriminatory ability of the RABBIT risk score was slightly poor, with an AUROC of 0.67 (95% CI, 0.52– 0.79). Conclusion The RABBIT risk score is highly practical; however, our present study suggested that some adjustments may be required to predict the risk of serious infection in Japanese patients with RA starting a first bDMARD. Figure 1. ROC curve of serious infection and RABBIT score with an AUROC of 0.67 (95% CI, 0.52– 0.79). Disclosure of Interests Tomoaki Higuchi: None declared, Eiichi Tanaka Speakers bureau: Abbvie, Asahi Kasei pharma co., Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo Co., Eisai Pharmaceutical, Janssen Pharmaceutical K.K., Nippon Kayaku, Pfizer, Takeda Pharmaceutical, Taisho Toyama Pharmaceutical Co., and UCB Pharma., Paid instructor for: Abbvie, Asahi Kasei pharma co., Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo Co., Eisai Pharmaceutical, Janssen Pharmaceutical K.K., Nippon Kayaku, Pfizer, Takeda Pharmaceutical, Taisho Toyama Pharmaceutical Co., and UCB Pharma., Eisuke Inoue Speakers bureau: Bristol-Meyers and Pfizer, Consultant of: Nippontect systems, Mai Abe: None declared, Kumiko Saka: None declared, Eri Sugano: None declared, Naohiro Sugitani: None declared, Yoko Shimizu: None declared, Moeko Ochiai: None declared, Rei Yamaguchi: None declared, Katsunori Ikari Speakers bureau: Asahi Kasei Pharma Corp., Astellas Pharma Inc., AbbVie Japan GK, Ayumi Pharmaceutical Co., Bristol Myers Squibb Co., Ltd., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Eli Lilly Japan K.K., Janssen Pharmaceutical K.K., Kaken Pharmaceutical Co. Ltd., Mitsubishi Tanabe Pharma Corp. Pfizer Japan Inc., Takeda Pharmaceutical Co. Ltd., Teijin Pharma Ltd and UCB Japan Co. Ltd., Yamanaka Hisashi: None declared, Masayoshi Harigai Speakers bureau: AbbVie Japan, Ayumi, Boehringer Ingelheim Japan, Bristol-Myers Squibb, Chugai, Eisai, Eli Lilly Japan, GlaxoSmithKline, Kissei, Pfizer Japan Inc, Takeda, Teijin, Consultant of: AbbVie Japan, Boehringer Ingelheim Japan, Bristol-Myers Squibb, Kissei, Teijin, Grant/research support from: AbbVie Japan, Asahi Kasei, Astellas, Ayumi, Bristol-Myers Squibb, Chugai, Daiichi-Sankyo, Eisai, Kissei, Mitsubishi Tanabe, Nippon Kayaku, Sekiui Medical, Shionogi, Taisho, Takeda, Teijin.